For many years, rotary valve structures have been connected to control an automatic water softener of the type including a bed which is periodically backwashed and then regenerated with brine withdrawn from a brine compartment or tank formed either as a part of the softener itself or as a separate unit. Many of such water conditioning systems include complicated valving to provide multiple functions such as service, backwash, brine, rinse and flushing of the system.
One known system is constructed as a closure to the open upper end of a mineral tank and functions in conjunction with a brine tank to provide a service mode, a backwash mode, a brine mode, a slow rinse mode and a rapid rinse and brine tank refill mode. The valve assembly in such system is motor driven in response to a timing mechanism associated therewith to enable automatic cycling of the valve assembly through the various modes, as disclosed in U.S. Pat. No. 4,210,532 issued on July 1, 1982, to Harvey L. Loke.
However, the disclosure of Loke is in fact only applicable to valves manufactured by conventional machining processes involving non-ferrous cast, forged or bar stock materials. Flatness specifications necessary for sealing surfaces require machining and lapping operations on these materials to maintain a minimum tolerance of 0.0004 inch to assure proper function. Both the material and the processing required are economically contrary to market requirements for cost competitive products. Additionally the electromechanical power requirements needed for rotary actuation against the relatively large area of sealing surface presented by the Loke valve only magnifies the problem of cost efficiency.
Other art relating to multiple port rotary type valves is disclosed in U.S. Pat. No. 2,451,678 issued on Oct. 19, 1984, to Bruce W. Johnson et al; U.S. Pat. No. 3,863,675 issued on Feb. 4, 1975, to Arthur J. Wiltshire; and Great Britain Pat. Specification No. 1,504,281 published Mar. 15, 1978, for inventor Ian Cooper.
Both the Johnson et al and Wiltshire patents address purely mechanical, hand-operated lift-and-turn structures. These non-automated valves are neither desired by the vast majority of the water conditioning market, nor is it economically feasible to impliment this complex actuation motion to automate its operation. Sealing members disclosed are completely without merit when considering simple and economic rotary shear action across the sealing surface. In other words, the tubular gaskets of Johnson et al and the gasket ribs of Wiltshire would be sheared off if used with rotary action valves of the Loke type instead of the lift-and-turn valves for which they were designed.
The Cooper disclosure reveals an effective seal surface pattern when applied to a rotary sealing member. However, as in the Loke disclosure, valve construction must rely on the costly non-ferrous materials and machining operations to achieve tolerance specifications necessary to effect bypass leak proof seals necessary for water conditioning control valves. Pointedly the Cooper disclosure makes no reference to seal composition or sealing function requirements.
U.S. Pat. No. 3,233,732 to Kenneth R. Lung et al discloses a water softening system employing a rotary valve wherein a spring urges a valve rotor made of phenolic resin against a valve plate which includes a rubber backup member and a wear resistant, self-lubricating, non-corrosive face plate preferably of polytetrafluoroethylene bonded thereto for sealing engagement with the rotor valve.
U.S. Pat. No. 3,470,151 to Lester O. Hegstad discloses a water softener rotary valve which employs a Belleville spring to urge a circular shaped planar face of a hollow rotor which is coated with polytetrafluoroethylene into tight sealing engagement with a circular shaped planar face of a stationary valve member cast of brass.
U.S. Pat. No. 3,123,096 discloses the use of a self-lubricating material such as polytetrafluoroethylene filled with glass, molybdenum disulfide, carbon or fine rouge in oxygen compressor feather valves.